Technical Field
The embodiments herein relate to optical systems, and more particularly to antireflective surfaces used in optical systems.
Description of the Related Art
In optical systems, Fresnel reflections from an optical surface have a variety of undesirable effects. These may include reduced transmittance, feedback into laser systems, stray reflections, and in the case of military applications, potential detection by enemy combatants. In bulk optics, Fresnel reflections are traditionally reduced using thin film dielectric stacks of materials with alternating high and low refractive indices. As a result of thin film interference effects, these stacks may be designed to behave as antireflective (AR) coatings for a range of wavelengths. Such coatings, however, may have several problems associated with them. For example, they may exhibit laser induced damage thresholds (LIDTs) significantly lower than those of the bulk optics, and may be subject to environmental degradations and delamination under thermal cycling, and may perform well only for a limited optical bandwidth and angular range. It is desirable to prevent these issues from occurring in an optical system.